Process for testing fluid ducts



Sept. 30,-1952 J, M, V m 2,612,037

PROCESS FOR TESTING FLUID DUCTS Filed Sept. 4, 1947 v 2 SPEETS-SHEET 1 FIG.! H62 8 7 I: II I I 2 l-l l I j FIG.3

INVENTOR.

Sept. 30, 1952 J. M. VAN ROOY 2,612,037

' PROCESS FOR TESTING FLUID DUCTS Filed Sept. 4, 1947 2 SHEETS-SHEET 2 FIG.5.

INVENTOR. Johann; FL in R00 BY 1am, W W

Patented Sept. 30, 1952 PROCESS FOR TESTING: FLUID DUCTS Johannes M. van Rooy, TheI-Iague, Netherlands, assignor of one-fourth to Hendrik Boer and one-fourth to Alida Johanna osterveen, bothof The Hague, Netherlands Application September 4, 1947, Serial No.

In the Netherlands September 23, 1946 6 Claims.

The invention relates to a process for determining the magnitude (size) of a leakage ina duct for a fluid, for determining the plac where there is a leakag in a duct, or for determining the diameter of a duct, and to a device for-the execution of said process.

Determining the place where there is a leakage in a duct is mostly time consumin and costly, particularly when said ducts are disposed for example in the ground, in houses, etc. .If, for example, a leakage should be found'in a house, the floors must be broken up for said purpose. Determining the diameter of ducts disposed under floors, in walls, between ceilings and in other places which are accessible with difficulty always involves breakage and repairing operations too.

Said disadvantages are avoided by the process according to the invention by the fact that a gaseous fluid or successively a'number of gaseous fluids is or are supplied tothe duct the specific weight of said fluid(s) differing from the fluid in the duct, until a sudden variation in pressure sets in in the duct. Here the property of gases is availed of that the exhaust speed of the gases from an aperture is inversely proportionate to the root of the specific weight of the ,gaseousfluids.

Air has a specific weight which is twice as large as that of the mixed gas used in gas ducts so that the exhaust speed of air through an opening is /2 or 1.4 times as small as that of mixed gas. 1

The amount of gaseous fluid which has been brought into a duct may then be measured, since, as soon as the gaseous fluid'brought into the duct has forced the gaseous fluid being'therein from the duct through the leakage, the pressure will suddenly rise or fall according as a fluid having a greater or a smaller specific weight is used. When the diameter of the duct is known, then it may be calculated with reference thereto where the leakage is in the duct. When the diameter of a duct is to be determined a puncture is made in said duct to cause a leakage and an amount of gas may be brought into the duct at a certain point from said leakage. As soon cording-to the invention is characterized in that a reservoir is filled one or a numberof times with a predetermined amount of gaseous-fluid, and the'amount of fluid is determined whichfhas flown from said reservoir into the duct; until the moment when in the fluid flowing'in'the jduct asudden change in prssure'dccurs; Herebyv it becomes possibleto make a compactfiand cheap device which may be applied .in-a'any required place and which" may be transported thereto easily.- Such a device may easily be: taken along bygasfitters.

' A 'preferred embodiment of the device for the execution of the process according to the invention is characterized .in that it is'=:provided 'with' at least one apparatus for bringing ajgaseousfluid into the duct and with a pressure responsive apj paratus which indicates the sudden change' in.

' pressure in the duct. As an apparatus for. bringing thegaseous fluid into the duct-"any device may be used, by means of which the fluidunder pressure may be brought into the duct: This may consequently be a hand pump as' well as a mechanically driven pump, a compressohvone or a number of reservoirs filled with the fluid under pressure,'etc. I.

The "pressure responsive apparatus need not indicate the pressure really prevailing in the duct,

but it is sufiioient that it indicates that a change in pressure sets in in the duct.

According to the invention the device 'forssupplying the fluid may beprovided with anapparatu's for measuring the amount of fluid which has been brought into the ductuntil the momentof the sudden change in pressure For measuring said amount anyknownzmeasuring apparatus maybe used, for example a gasmeter,

a rotameter, a bell, which is inaliquid filled reservoir, so that from the sinking of the .bell may be ascertained how much fluid, has been brought into a duct, etc. It is also possible to use a measuring apparatus providedzwith anempirical scale. When a compressor or other device-is applied-producing a determined: amount of. fluid per unit of time the time may be measured during which said device has operated until thesudden change in pressure ha occurred withreference whereto the amount of fluid suppliedmay for 'a gase'ousifluid under. pressure.

1 ing ranges;

Instead of the airpump 2' a container may be "connected to the reservoir in which' container there is'a'gaseous fluid under high pressure which Lisadmitted'intothecasing l by means of a reducing valve.

not necessary to check the device permanently until the sudden fall in pressure occurs.

A preferred embodiment of the device according to the invention is characterized in that it is provided with one or a number of pressure reducing means which maybeexecuted as flow limiting means or contractions of various sizes of the flow passage for the fluid to be supplied to the duct. Preferably said means are made adjustable.

The invention will be described more fully below with reference to the drawings in which by way The. device represented in the Figures 1-3 comprisesacasing'hin which a hand pump 2" is disposed with'iwhich air-.maybe pumped into the casing. [which contains a storage reservoir l4 This reservoir l4. communicates through a pipe 3 with a pipe stump 4 which is connected to the duct to becheckedlor measured by means of a rubber -=hose (not shown).

In said :pipe-a control means E -is disposed which may be adjusted with anicperating "means 6 10- cated 'on-cthe outside of the casing I; x-trol "means: serves to keepthe pressure of the Said congaseous.fiuid'rinia reservoir T constant. =Said pressure may be read fromagauget communi- =cating withsaid-reservoir I: Thepipe 3'is con ".nected. to the reservoir! by (means of a-branch duct.9. Saidbranch duct 9 extends :above the level. of a liquid in the-reservoir [being present intheunder part of said-reservoir. I

Furthermore the pipe 3 is connected through a branch'duct 10 to. a. second: reservoir II in which theretis also aliquid. The branchduct'lll extends againrabove the level of said liquid. The reservoir II is connected to a secondgaugel2 -ihaving 'a' more or less empirical scale.

' ,zln'the exampleillustrated-thei gauges B and i2 i-comprise: smallglass tubes in which the liquid level can be observed.

iBetweenthe'branchducts 9 and") in the pipe $3 a contraction or a' flowlimitingmeans l is dis- :f-posed preferably two or'more Of SllCh'gfiOW limit- Jing means being present,1so' that by means ofan operating handle l3zextendin'g outside-the casing I .thedevice may be adjustedto variousmeasur- .If one desires to determine if a gas duct is leaky one'proceeds as follows:

The device is. connected at an. arbitrary point to the duct to be checked, the main cock of the gas duct orlline is closed;and the control means 5 is adjusted in such a way thatthe pressure. of the fluid in the gauge 8 has the magnitude for which the empirical scale of the-gauge IZisgauged.

When the liquid :in the gauge I2 remains on the same level, the duct is-in order. If there is a-leak-.

the required. pressure.

age in the duct then the pressure loss of the flowlimiting means between the two gauges indicates the magnitude of the leakage which pressure loss may be read from the gauge l2. According as the leakage will be greater it will be necessary to open the control means 5 further in order to keep the pressureof the gauge at. the required value for which the pressure in the gauge l2 rises.

For determining the place where there is a leakage, for example in a gas duct, one proceeds as follows:

The device is connected again to the gas duct bymeansofa rubber hose secured to the pipe stump 4, whereafter the main cock of the gas duct or line is closed, and the control means is adjusted in such a way that the gauge 8 indicates When the column of the fluid brought into the gas duct reaches the leakage the pressure in the gauge 8 will suddenly rise or fall due to the slower or quicker outflow thrcughtheleakage of the fluid pumped into the gas duct and-the higher inletpressure. The time ismeasured. fromthe admissionofthe flui'dinto the gas duct .tillthesudden rise of the pressure indicated-by gauge .8 while from the empirical scale of the gauge l2 before the sudden rise of the pressurethe number of liters ofv gas is read,

which flows away through the leakage perminute. The'productof.thenumberof minutes which the fluid isadmitted into thegas ductand-the read .number of liters ofgasflowingaway. per-minute indicatesthe contentsof the duct betweenthe device andtheleaka-ge.

A table .uponwhich1the contents otpipes .having different. diameters .per meter are indicated makes it easy to. determinethe length .ofv the. duct.

"If,'for example, a leakage of l./h. has been registered and the time of supply. of thefluid to the. gas duct until the sudden change in pressure occursamountsifor example to.1.4=- minutes .ithe total amountv of fluid'pumped in is Assuming: that the duct has a diameter or /1. a

lengthoi-Bm. is read'from thetable (the con- "tentsof-Im. of gas duct with a diameter'of'%" is'namely 280 cmfi) For determining the "diameter or a duct e. g. under. a floor orin a wall one proceeds asfollows: At one :end of. the ductca small leak" is made by means of a small tap, and the device isrc'onnectedto the. other end: ofthe duct. In the .same

-way as indicated abovewitlr regard tolthe' search for a leakage the :amountzof the fluid-brought into said duct is measured. JAfter measuringthe length of the-duct thediameter of the :ductmay "be; calculated orabe read from a table prepared for said purpose.

Intheembodiment accordin to Figure-:4. a

small gasmeter 21'- is connected through a-pipe '22: to a compressor 23. Said compressor may be made in such-a way that gas having a constant pressure :is supplied therefrom. The compressor -is a control cock 25 to a-pressuregauge 26 which 23 is connected througha pipe 24 in'whichthere is provided-witha pipe stum 21 which isconnected through a fiexiblehose 28v toa liquid duct 29 which must be checked forgas leakages.

Theabove-described device operates as f ollows: After the device has-been connected to the liquid-duct 29 the compressor isrput into action and thecontrol cook 25 is adjusted in such a way that the gas with'a predetermined constant pressure is" supplied to. the duct 29. The amount ioflgas through the leakage.

just before the pears.

- is measured by means of asmall; gasmeter 2|.

As soon as the gas, for example-air, has "reached the leakage, it will flow away more" rapidly reaching the leakage, and 400 liters of gas were supplied, the contents of the duct to the measuring place are 0.5 400 litres=200 litres.

I If the section of the duct is 100 cmF'then the'leakage I is consequently between I new or 20 m. from the measuring place.

The magnitude of the gas pressure at any arbitrary moment is of no importance, but only the pressure of the gas in the duct need be measured pressure suddenly falls or 'disap- I It is stated that when defining th place of a leakage theliquid sometimes flows away from the duct so rapidly that a constantpressure canair, a gaseous fluid should be used which has anfor example-mixed gas or carbonic acid. a

not'be maintained at the beginning of the gas I supply. According as, hOWGVEiythB liquid column in the duct will fall, the pressure exercised by the liquid-column above the leakage will become smaler' and smaller, so that the outflow speed of the liquid through the leakage will decrease regularly. Hereby the gas in' the duct will practically alwayshave the predetermined constant when reaching the leakage with small overpressures of the gas supplied so that practically always a gauge may be used which is not provided with a. scale or comprises a rough scale;

The gauge 28 as well as the gasmeter 2! may [be self-registering. Hereby mistakes on reading are avoided whereas the operation of the apparatus becomes easy. Furthermore thegauge may be provided with an adjustable stop, if'requried,

which stops the supply of gas with the sudden fall of the pressure.

, In Figure 5,.3l is a reservoir which provided with a hand air pump 32 withwhich the reservoir may be filled to the required pressure. By the fact that a motor is not necessary the device ac- .cording to the invention may be used in anyrequired place. A pressure responsive apparatus is provided with at least one scale 33 on which the number of liters of gas flown out of the reservoir at a predetermined presssure may be read. Said scale may be obtained by calculation so that an empirical gauged scale is not necessary.

The reservoir 3| is provided with a pipe stump 34 in which a cook 35 is provided. Following said cock in the pipe a gauge 38 is disposed. The pipe stump 34 may be connected to a duct to be checked by a hose. I

If it is required to determine the place of a leakage'in a vertical liquid duct by means of said device the cook 35 is slowly opened, so that it is wholly open as soon as about half or less of the gas has flownout of the reservoir 3|. The number of liters of gas flownout of the reservoir 3| quired the apparatushaving the scale 33 may also be made self-registering.

If the duct to be checked should be filled with I the amount of fluid flown out ata determined pressure or about at said. pressure 'maybe read other specific weight than air,

'When a gas duct is'checked air as a gaseous fluid may be used. In this case a rise in pressure in the duct indicates the moment at -which the air reaches the leakage. I I

It is clear that in the above only an embodiment 'by way of example has been represented, and that the device may be varied inseveral ways without departing from the scope of the invention. Forexample', carbonic acid tabletsmay be used producing a predetermined-amount of gas. The second'reservoir may also be filledfa number of times with a fluid having a determined pressure during the checking operation. The first reservoir is then emptied to a determined limit, wher'eafter the valve inthe connecting stump of the first reservoir is closed and the valve between the two reservoirs is opened till a compensa'tiori of pressure inthe two reservoirshas set in. Then the amount of gaseousfluid which has supplementary been brought into the reservoir is known exactly. Ifrequired this may be repeated some times. Due to said construction as well as byoperating with'ma's'ses yieldingia predetermined amount. of gaseous fluid the .dimensions of the device according tothe invention may be decreased considerably. Ifjthe second reservoir is also provided with an apparatus with which the amount of fluid flowing out oifit ma be measured it is evidently not necessary 'close the cook 35 when one desires to replenish the reservoir 3|. When the second reservoir isjprovided with such a measuringapparatus themeasuring apparatus in the first reservoir may be liminated. After the cock 35, has beenjclosed in case of a sudden fall or rise of the pressure the valve between the two reservoirs is wholly opened, and, after the pressure compensationhas set in from said measuring apparatus I or calculated .by means thereof. The scale maybe eXecuted in su' ch away that a direct readingboth of the amount pumped orbrought intojthe second reservoir and the amount of gaseous fluidflowing out of the device is possible. i

It is stated that an the above-assented at merits may be disposed in or on the deviceso that a' unitary device is obtained. 5

It is clear that various other constructions of the reservoirs may be designed with which the process according to the invention maybeexecuted. For example the one reservoir maybe made to. switchin the-other, when the former I reservoir is empty, whereby simultaneous'ly the connection of the latter reservoir to the duct is interrupted, and said reservoir is filled again automatically, etc. The reservoirs may"also"be "filled manually, etc. The constructions of such reservoirsdo not involve any difilculties for some I one skilled in the art. 1

If the above-describeddevice is used for checking vertical or sloping ducts filled with liquid the outflow speed of the gaseous fluid used differs so much from that of liquids that when the gas reaches the leakage it will escape so readily through the leakage that the pressure is'suddenly eliminated. In this case the scale 33 already indicates the fall in pressure so that with an opened cock the gauge-351s reallyj superfiuous, II I In the embodiment according to figure-5 the amo'unt'of gaseous fluid brought into theduct --:may: be determined .in a. simple manner by. de- Itermining the amount of gaseous fluid being in the reservoir at the moment when the sudden .-.change inpressure sets in and bysubtra'cting said-.-amount-irom the amount being originally in the reservoir.

When checking gas ducts in private houses the ..zpressure of the fluid brought into the duct'need "only be low and an overpressure of'for example 10 cm. of water is already suflicient. :The valve .is adjusted in such a way that "said pressure is .indicatedg-bythe gauge 36. -During the outflow fot; thegaseous fluid from the reservoir the ,pressure -therein -will fall,--whereby the pressure in .thegauge will-also fall slowly" If required the valve35:may beadjusted somewhat during the outfiowso that the pressure in the .duct keeps thegvalue adjusted initially or reaches it again. ,Since,.- however, the overpressure in the. duct is flow rather great differences in the pressurein- .dicated by thegauge will not influence the exact- :ness of the .measuring apparatus in the reservoirlior .theamount ofi'luidfiown out.

.In order toindicate clearly. the change in pres- ..sure ofthe fluid in theduct the pipe of the gauge 3 6.maybe helical, whereby with a small change in pressure the liquid in this case displaces itself along a' largedistance in the pipe.

.TIt will be understood that in the above only ,someembodiments of thedevice according. to the invention have been given and that it may be varied in numerous Ways without departing from "thescopeof the invention. This applies both to f the apparatus for bringing the gaseous fluid into theduct, and for the apparatus for measuring the amount and the pressureof the fluid brought into the duct, and for the apparatus for indicat- "ing the sudden change in pressure occurring in the fluid. Herefor all apparatus known per se "may be used.

l. .Ifq a m 1'; A'prpcess' for leakageidetection in' a fluidfilledflduct comprising introducing a gaseoustestingmedium into said duct from a source of supply, said gaseous testing medium differing in specificweightfro'm the specific weight of the gaseousmedium normally within the duct, and continuously measuring the pressure of said mediums until suchmeasurement indicates a sudden'phange'of pressure producedby the dinerential between/said'specificweights at the point of leakage.

..f2.jAi. process fonleaka'ge'detection in afluid- "fillediduct'comprising introducing irom .a source oi s upply ajgaseous testing medium into a.pres- 'su'rearesponsive' apparatus and thence into said Educt saidgaseous testing medium differingyin *qspecificWeight from the. specific. weight of the gaseous medium normallyewithin said duct,.and continuing the introduction. of said gaseous testfing-tmedium untilj said pressure-responsive ap- "paratus"iridic atesa sudden change ofpressure produced by the differential. between-the specific weights of said mediums'jwhen the gaseous testingi medium reaches 'a, point of leakage.

23; Aprocess'for testinga fluid-filled Zductfor ""thepointof leakage comprising supplying at least "10118; gaseous testingfiuid'to said duct until the "jmoment when a sudden change in pressure of the fsupplied gaseous testing. 'fiuid occurs, the specific "'gweight of said supplied gaseous testing fluid .dif- "fering'f rom the specific weightof the. fluid be- "ing present in said duct, measuring the amount of gaseous testing fluid introduced into. said duct j until jthei mcment when the 'sudden. change .in

pressure occurs and from the ratio of theiiuid introduced tothe volume of. said duct calculating the point of-leakage.

I :4. A process for testing a fluid-filled duct for 'the 1 point of leakage comprising supplying. at

least one gaseous testing fluid-to said duct until 1 the moment when a sudden change in pressure of the supplied gaseous testing fluid occurs, the

specific weight of' said suppliedzgaseous' testing .-fiuiddifiering fromgthe specific weightwofthe -fiuid being-present in said duct, measuring the amount and the' pressure of the testing fiuidin- ..'in. a--fluid-filled duct comprising introducing a gaseoustesting medium into said duct from a source of supply, said-gaseous testing medium difiering in specific weight from thespecific weight of the gaseous medium normally within the duct,.and continuously measuring the pressureof said mediums until such measurement indicatesa sudden change of pressure produced by thgdifierential between said specific weights at the point of leakage, continuously measuring. the

1 volume ofasaid gaseous testing medium intro- ,duced into'said duct until the measurement of the. pressure of said mediums indicates said sudden change and thereafter. calculating from such. measurements and the volume. of saidduct .the distance between the point of introduction .of said, gaseous. testing .medium. and the point of leakage.

6.. A process-for detecting .the point of leakage in a fluid-filled duct comprising introducing from a source of supply a gaseous testing mediuminto a pressure-responsive apparatus and thence into said duct, said'gaseous testing medium difiering in. specific weight. from the specific weight of .the

gaseous medium normally within said duct, and

f continuing the introduction of said gaseoustesting medium until said pressure-responsive apparatus indicates. a sudden change of pressure produced .by. the differential between the specific weights of said mediums when the gaseous testing medium reaches a point. of leakage, measuring the volume of testing medium introduced until said pressure-responsive apparatus indicates said sudden change of pressure and thereafter calculating from such measurement and the volume of'saidduct the distance between the point ofintroduction of the gaseous testing'medium and the point of leakage.

' J OHANNES M. VAN ROOY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain Oct. 22,1940 

